Distillation apparatus



Oct. 26, 1965 A. N. WELLS 3,214,352

DI STILLATION APPARATUS Filed NOVf27, 1962 2 Sheets-Sheet 1 INVENTOR ARTHUR N. LUELLS BY MM! m ATTORNEYS Oct. 26, 1965 N, WELLS 3,214,352

DISTILLATION APPARATUS Filed NOV. 27, 1962 2 Sheets-Sheet 2 "'ISO INVENTOR Nan-m2 M. wens ATTORNEYS United States Patent 3,214,352 DISTILLATION APPARATUS Arthur N. Wells, R0. Box 6%, Belmont, Calif. Filed Nov. 27, I962, Ser. No. 240,229 1 Claim. (Cl. 202-187) This application is a continuation-in-part of my copending application Serial No. 843,473, filed September 30, 1959 and now abandoned.

This invention relates to distillation devices, and more particularly to distillation devices which operate on the vapor compression principle.

The major function of the invention is to convert saline or brackish water into fresh water, however, the invention may be used for distilling other fluids.

An object of this invention is to provide a distillation device which operates on the principle of vapor compression without many of the inherent disadvantages existing in vapor compression distillation means of the prior art.

Another object of this invention is to provide the vapor compression cycle without the use of a mechanical compressor.

Another object of this invention is to provide the vapor compression cycle without the use of conventional steam jet compression means thereby eliminating the use of a boiler with extensive piping and controls as well.

Another object of this invention is to provide devices for distilling fluids which avoid the superheating of compressed vapors as normally would occur in conventional devices which employ mechanical compressors and steam jet systems.

Yet another object of this invention is to provide distillation devices which avoid the use of cold distillate for the purpose of de-superheating of the vapors so as to eliminate substantial heat losses.

Yet another object of this invention is to provide distillation devices that are of compact construction which are easily insulated against heat losses, are economical and simple in design, are durable in use and require a' minimum of maintenance.

Yet another object of this invention is to provide distillation devices which employ venturi type aspirators in a new and novel manner.

Still another object of this invention is to provide distillation devices which employ venturi type aspirators so as to draw bubbles of vapor into a stream of hot distillate liquid so as to form a foam wherein the vapor bubbles are compressed, to direct this foam through heat ex change coils which are immersed in boiling liquid, so as to condense the vapors and to add the heat of vapor condensation to the boiling liquid so as to produce more vapor.

Yet another object of this invention is to obtain a new distillate by permitting overflow from the distillate that is circulating through an aspirator which is constantly drawing in fresh vapors.

In conventional vapor compression systems of distillation devices, mechanical means or steam jets are used to provide the pressure differential that is needed between the boiling and condensing fluids. These conventional devices not only are mechanically complicated, cumbersome and expensive, but also have the inherent problem of superheating of the compressed vapors used therein. In order to condense the superheated vapors in these conventional devices, it is necessary to de-superheat these vapors. This is accomplished by adding cold distillate or other cold liquids to the superheated vapors. When this is done, nearly all of the mechanical energy or heat energy that was applied in compression becomes lost to the cold liquids which are added for de-superheating. In

3,214,352 Patented Oct. 26, 1965 the present invention, the vapors are compressed by a venturi-aspirator. Flow through the venturi is exerted by a pump which circulates hot distillate that is near its boiling point. As the hot distillate flows through the venturi-aspiraor, the pressure thereof is reduced whereby vapor from the boiling liquid is drawn in and mixed with the hot distillate. As the mixture of distillate and vapor bubbles pass out of the aspirator, the bubbles are compressed and the temperature of the mixture therefore becomes somewhat greater. However, while the vapor bubbles are compressed they do not become superheated because of the surrounding wetness of the distillate and may be easily condensed in such a manner that no heat is wasted. This is a substantial improvement over prior systems and devices for distilling liquids by vapor compression means.

The invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawings, wherein:

FIG. 1 illustrates a simplified form of my invention;

FIG. 2 illustrates a practical form of my invention.

Referring now more particularly to the drawings, the reference numeral 10 designates in general a large pressure or heating vessel preferably oriented so that its axis extends in a general vertical direction. The vessel 10 contains a body of liquid 11 which is to be distilled. The vessel It) is provided with means preferably at its lower end for heating the liquid 11, and as illustrated in the drawings this heating means comprises electric heaters such as those indicated by reference characters 12 and 13 which are connected to a source of electricity by conductors 14 and 15 extending through the side wall of the vessel 10.

Of course, any other suitable means for heating the vessel may be employed.

The apparatus shown in the drawings is a system in which the body of liquid Ill within vessel 10 may be termed the primary system and a secondary system, which consists of a heat exchange unit indicated generally by the reference character 16 located within the vessel 10 and associated conduits and elements connected thereto and within which the distillate is continuously circulated during operation of the apparatus.

The primary system begins with the fluid to be distilled, fed through pipe 64. Pipe 64 connects to a vertical shell-and-tube heat exchanger 62, entering at the bottom end. The fluid gains heat as it moves upward through heat exchanger 62, emerging at its upper end into pipe 32. Pipe 32 then connects to valve 31 which is a part of float valve assembly 30. Float assembly 30 is used to control the liquid level within vessel 10 by modulating the flow through valve 31, into pipe 33. Pipe 33 then conveys the fluid to the lower region of vessel 10, terminating at port 34.

The liquid level in vessel 10 is maintained substantially as shown at numeral 11, and this level is the same as the float operating level in float assembly 30. The float chamber of assembly 30 has pipes 35 and 36 connected to vessel 10, so that pipe 35 relates liquid to the float chamber, while pipe 36 provides a vent to the vapor space 43 of the vessel, so that correct level is contained therein.

The vessel It) is provided with heat exchanger 16, which may exist as a bank of coils 17, with inlet connection as pipe 18 and an outlet connection as pipe 19. This heat exchanger 16 may be formed of tubes and sheets as a matter of alternate design.

Vessel 10 also has a bottom drain outlet 50 with control valve 51.

Thermometer 70 and pressure gauge 68 are provided to indicate the operating conditions within vessel 10.

At the top of vessel 10 is an opening with check valve 66, and pipe 42 connecting said check valve to the suction inlet of a venturi-aspirator 40.

Vessel is also provided with heaters 12 and 13 near the bottom to add heat to the fluid to be distilled. Heaters 12 and 13 are provided with electric power connections 14 and 15, however, other methods of supplying heat could likewise be applicable in that region of vessel 10.

The secondary system begins with circulating pipe 25 which conveys hot distillate fluid to the section port 24 of pump 22. The pressurized discharge of pump 22 is conveyed by pipe 21 to a venturi-aspirator shown generally as reference character 20. The aspirator 20 is composed of a body 40, and has a venturi with a restricted throat at 41, an opening to the restricted zone for pipe 42, and an axial outlet to pipe 18.

Pipe 18 conveys fluid from venturi-aspirator 20 to heat exchanger 17, and the fluid passes thence through pipe 19 to a junction of pipes 25 and 26. Pipe 26 rises upward, through heat exchanger 62 to an outlet spout 27. Spout 27 is generally placed at a high elevation to maintain a pressure head on the secondary system.

In actual practice it is customary to insulate vessel 10 as well as all of the piping and apparatus shown in FIG. 1. In the case of a large sized version of the apparatus, the whole of it may simply be placed in an insulated building or structure.

In operation, the vessel 11) is substantially filled with liquid to be distilled such as sea water by means of conduits 64, 32, and 33 which are connected to a suitable source of supply. The float controlled valve 31 automatically maintains the liquid 11 at the desired level within vessel 10 as illustrated in the drawings.

The secondary system is filled with distilled liquid such as pure water at least to the level of outlet pipe 19, preferably to the top of stand pipe 26. Liquid 11 is then heated by means of electric heaters 12 and 13 so as to cause the liquid mixture 11 to vaporize thereby filling the space 43 in the upper portion of vessel 10 with distillate vapors. The pump 22 is energized so as to circulate distillate through the secondary system as indicated by the arrows in FIG. 1. As the distillate passes through the restricted throat 41 of the aspirator or venturi 20, a reduced pressure is created at this throat thereby sucking vapors from region 43 through check valve 66 and conduit 42. As the vapors pass from conduit 42 into the aspirator, they mix with the liquid distillate flowing through the aspirator and form a plurality of bubbles in the liquid distillate thereby creating a foam of liquid and vapor. As this foam then passes into the inlet conduit 18, the vapors are compressed by the velocity of the mixture being ejected from the venturi thereby reducing the size of the vapor bubbles, increasing the pressure of the vapor bubbles and raising the temperature of the vapor bubbles and foam mixture. However, even though the temperature of the vapors in conduit 18 is increased by the increased pressure, there is no superheating effect because of the available wetness of the admixture of liquid distillate.

As the foam mixture of distillate and vapors pass from the conduit 18 into the heat exchanger coil 17, the foam is cooled to a lower temperature by the liquid 11 thereby causing the vapors in the foam to condense which obviously increases the amount of liquid in the heat exchanger 16 and the secondary system. By the time the fluid reaches outlet conduit 19, substantially all of the vapor bubbles have been condensed. Since the volume of the liquid distillate in the secondary system is being constantly increased due to the condensation of the vapors drawn from the vessel 10, this excess liquid must be drawn from the secondary system. This is accomplished by permitting the excess distillate to flow upwardly through the stand pipe 26 and out of the discharge spout 27. As the distillate flows from the discharge spout 27, it may be collected in a suitable container or vessel. It is to be noted that as the hot distillate flows through the stand 4 pipe 26, it also flows, through the heat exchanger 62 thereby heating the liquid flowing from pipe 64 to the vessel 11) and increasing the efficiency of the system.

Since the aspirator 2th creates a suction within the region 4-3 of the vessel 10, the pressure within the vessel is substantially reduced thereby permitting the liquid 11 to boil or vaporize at a relatively low temperature. It is to be noted that as the vapor bubbles condense within the coils 17, they give 011? a substantial amount of heat thereby raising the temperature of the liquid 11 so as to cause it to continuously boil or vaporize. Since heat is continuously being added to the liquid 11 by the condensation of vapor in the heat exchanger coil 17, once the distillation apparatus has been started in operation, the electric heaters 12 and 13 may be partially cut off whereby most of the energy for boiling or vaporizing the liquid 11 is supplied by the pump 22.

In order to increase the efficiency of operation, the drain vale 51 is periodically opened so as to drain the concentration of impurities which accumulate at the bottom of the vessel 10. Alternatively, the valve 51 may be continuously left open a desired amount so as to continuously drain ofl? impurities and the concentrated liquid formed in the vessel.

The form of my invention illustrated in FIG. 2 is a more practical arrangement than the form shown in FIG. 1 and includes a tank or vessel '72 having a large diameter upper portion 74 connected to a small diameter elongated lower portion 76 by a frusto-conical wall 78. The upper end of the tank is sealed by a top plate 89 which is bolted to flange 2% with bolts 2tt1, and the bottom of the tank is sealed by bottom wall 82. A pressure gauge 84 is mounted on the plate and connected to the interior of the tank so as to measure the pressure therein. A conventional thermometer 86 is operatively connected to the lower portion of the upper portion 74 so as to measure the temperature of the liquid 38 in the upper portion of the tank. Preferably, all portions of the tank 72 are of circular cross sectional shape. The lower or stem portion 76 of tank '72 contains a well 96 which has an open top and a closed bottom that extends through the bottom wall 82 and projects downwardly therefrom. The liquid to be distilled is supplied to the tank 72 by a source of supply connected to the inlet conduit 92 which in turn is connected to the inlet side of a float controlled vale 94. The outlet of the valve 94 is connected to the bottom of the well 91) by means of a conduit 96. A float control 98 is connected to upper and lower portions of upper tank portion 74 by means of conduits 100 and 102. The float control 98 is operatively connected to the valve 94 so as to maintain the level of the liquid 83 below the top plate 80 as shown in FIG. 2.

A separating tank 104 surrounds the stem 76 and is connected thereto by bottom wall 1116 and frusto-conical top wall 108. An annular space is defined between the separator tank 104 and the stem 75. This space 110 is divided into two annular compartments 112 and 114 by a baflle plate 116 which surrounds stem 76, is connected to the bottom wall 196 and extends part way upwardly into the space 110.

The secondary system for circulating and condensing distillate includes an aspirator or venturi 118 similar to the aspirator 20 in FIG. 1 and having a restricted venturi throat 120 operatively connected to a vapor space 122 in the upper portion of tank 72 by means of an L-shaped conduit 124 and one-way check valve 125 which permits flow only in the direction of the arrow. The aspirator or venturi 118 has its outlet connected to a heat exchanger 126 which comprises a plurality of coils 128 extending downwardly through the liquid mixture 88 in the upper portions 74 of tank 72. The outlet of the heat exchanger is connected to a vertical pipe or conduit 130 which extends downwardly through the stem 76 and well 90. The lower end of the pipe 131} extends through the bottom of the well 90 in sealing relation therewith and is connected to a T-fitting 132. The one outlet of the T-fitting 132 connected to the drain valve 138 to empty the system. The other outlet is connected to a stand pipe 134 by means of a horizontal pipe 136. The outlet of the stand pipe 134 extends substantially above the top of tank 72 and terminates in an outlet spout on nozzle 140.

The secondary system also includes a short horizontal conduit 142 connected to the pipe 130 and terminating within the compartment 112. The compartment 114 is connected to the inlet of a power driven pump 146 by means of a conduit 144 and the outlet of the pump 146 is connected to the inlet of the venturi aspirator 118 by means of an L-shaped conduit 148 which enters into vessel 172 at point 202.

The uppermost portion of the annular space 110 in the separator tank 104 is vented to atmosphere by a vent pipe 150.

The bottom portion of the interior of the stem 76 is divided into two annular concentric chambers 152 and 154 by the walls of well 90.

The compartment 114 is provided with drain valve 156. The annular chamber 152 is provided with drain valve 158.

The heating chamber 162 surrounds the frusto-conical wall 78 and is defined by an annular insulating wall 164 of J-shaped cross section and the frusto-conical wall 78. Heating chamber 162 contains an annular heating coil 166 which is connected to a suitable source of electricity.

The basic principle of operation of the form of my invention shown in FIG. 2 is virtually the same as the principle of operation or the form of my invention shown in FIG. 1. The inlet conduit 92 is connected to a source of liquid mixture 88 to be distilled. This mixture is conveyed to the tank 72 by the conduit 92, valve 94, conduit 96 and well 90.

In operation, the tank 72 is substantially filled with mixture 88 by means of the conduit 92, valve 94, and conduit 96 to substantially the level indicated in FIG. 2. The level of the fluid mixture 88 is controlled by the float control 98. Since the top of the mixture 88 is spaced below the top plate 80, a vapor space 122 is provided in the upper portion of the tank.

The secondary system including conduits 148, 130, 142, space 110, pump 146, and aspirator 118 is preferably filled with liquid distillate to a level above the aspirator. The electric coil 166 is energized by a suitable source of electricity so as to heat the mixture 88 and cause vapors to form in the vapor space 122. The pump 146 is energized so as to pump pure liquid distillate through the secondary system as illustrated by the arrows in FIG. 2. As the liquid distillate is pumped through the venturi aspirator 118, a suction is created by the restricted flow 120 which in turn sucks vapor from space 122 through check valve 126 and conduit 124. The vapor passes into the venturi and mixes with the liquid distillate therein to form bubbles in the distillate, which results in a foam of bubbles and liquid distillate. As this foam is ejected from the aspirator into coils 128, the bubbles in the foam are compressed, thereby creating an increased pressure on the foam in the heat exchanger 126. The compression of the foam also raises the temperature thereof above the temperature of the mixture 88. The mixture 88 surrounding the heat exchanger cools the heat exchanger and the foam therein, thereby causing the vapor bubbles to condense and thereby increase the amount of liquid distillate in the secondary system. The increased amount of distillate flows upwardly through stand pipe 134 and out of the nozzle 140 where it is collected in a suitable receptacle, not shown. It is again to be noted that the heat of condensation of vapor within the coils 128 is transmitted by means of heat exchanger 126 to the mixture 88, thereby raising the temperature thereof, or at least maintaining the temperature thereof, so as to con- 6 tinue the boiling or vaporization of the mixture. Once the cycle has been started, the electric coils 166 may be reduced in power and the main energy supplied to the distillation apparatus is furnished by the pump 146.

It is to be noted that the distillation apparatus in FIG. 2 has its various parts so designed and arranged to eliminate substantially all waste of heat. When the distillate flows downwardly through pipe 130 and well 90, the incoming mixture flowing upwardly through chamber 154 is heated bythe downwardly flowing distillate, thereby removing substantially all the heat from the distillate discharged through the nozzle 140. Also, it eventually becomes necessary to drain the stem 76 by means of the drain valve 158 so as to remove concentrated impurities, resulting from the vaporization of the mixture 88. As these impurities are drained from the stem 76 they flow downwardly through chamber 152 and thereby transmit their heat to the incoming fresh mixture flowing through chamber 154. This heat is transmitted through the walls of well which is composed of a material having a high heat conductivity, such as copper.

It also should be noted that when the distillate is circulated, it is discharged from the conduit 142 into compartment 112, where it flows upwardly over the baffle 116 and into compartment 114, so as to be drawn into pump 146. As the distillate flows over the baflle 116, all gases therein rise to the uppermost portion of chamber and are vented therefrom to the atmosphere by vent pipe 150.

It is also to be noted that the liquid distillate in compartment 112 transmits additional heat to the mixture 88 through the walls of stem 76. Also, distillate heat transfer occurs through the walls of conduits and 142.

From the above, it can be seen that all fluids drained from the apparatus by means of conduit 136 and valve 158 transmits substantially all of their heat into the incoming liquid passing through chamber 154, thereby pre venting loss of heat and energy from the apparatus.

As explained above, in relation to FIG. 1, the apparatus shown in FIG. 2 may have its various components properly insulated for additional conservation of heat.

It is to be noted particularly that the above described devices avoid the necessity of de-superheating vapors by injecting cold condensate therein, thereby resulting in a substantial saving in heat which is absolutely impossible with any other example of the prior vapor compression art.

Inasmuch as various changes may be .made in the form, location and relative arrangement of the several parts without departing from the essential characteristics of the invention, it will be understood that the invention is not to be limited except by the scope of the appended claim.

I claim:

Distilling apparatus comprising a tank including a lower portion and an enlarged upper portion, said upper and lower portions defining a closed chamber therewithin, liquid inlet means extending upwardly from the bottom of the lower portion and terminating within said lower portion for introducing a liquid mixture within said closed chamber, heat exchanger means disposed within the upper portion of the apparatus and including a downwardly extending portion extending through and centrally within said inlet means, said downwardly extending portion being connected with liquid outlet means, means for maintaining a constant liquid level in the appaartus and defining a vapor space thereabove within said closed chamber, liquid-powered aspirator means including an inlet and an outlet, the outlet portion of said aspirator means being connected with said heat exchanger means in the upper portion of the apparatus, pump means for supplying liquid under pressure to said aspirator means, said pump means including an inlet and an outlet, means connecting the outlet of said pump means with the inlet of said aspirator means, means connecting the inlet of said pump means with said downwardly extending portion of the heat exchanger, said last-mentioned connecting means including gas separator means therein, means connecting an intermediate portion of said aspirator means With the vapor space defined Within the apparatus, and means for heating the liquid mixture Within the upper portion of the apparatus.

References Cited by the Examiner UNITED STATES PATENTS 585,365 6/97 Skiffington.

849,579 4/07 Siebel 202-75 1,361,834 12/20 De Baufre 20275 2,619,453 11/52 Andersen.

2,803,590 8/57 Skow 20275 X NORMAN YUDKOFF, Primary Examiner. 

